Additive for Polyolefin Polymerization Processes

Abstract

A polymerization process is disclosed, including: polymerizing at least one olefin to form an olefin based polymer in a polymerization reactor; and feeding at least one ethyleneimine additive to the polymerization reactor. The ethyleneimine additive may comprise a polyethyleneimine, an ethyleneimine copolymer, or a mixture thereof. The process may further comprise monitoring static in the polymerization reactor; maintaining the static at a desired level by use of at least one ethyleneimine additive, the at least one ethyleneimine additive present in said reactor in the range from about 0.1 to about 50 ppm, based on the weight of polymer produced by said combining.

1 . A polymerization process, comprising:
 polymerizing at least one olefin to form an olefin based polymer in a polymerization reactor; and   feeding at least one ethyleneimine additive to the polymerization reactor, wherein the ethyleneimine additive comprises a polyethyleneimine, an ethyleneimine copolymer, or a mixture thereof.   
     
     
         2 . The polymerization process of  claim 1 , wherein the ethyleneimine additive is fed to the reactor in an amount ranging from 0.01 to 200 ppmw, based on polymer production rate. 
     
     
         3 . The polymerization process of  claim 1  or  2 , wherein the polyethyleneimine additive is fed to the reactor in an amount ranging from 0.05 to 50 ppmw, based on polymer production rate. 
     
     
         4 . The polymerization process of any one of  claims 1 - 3 , wherein the ethyleneimine additive has a number average molecular weight of less than about 100000 Daltons. 
     
     
         5 . The polymerization process of any one of  claims 1 - 4 , wherein the ethyleneimine additive has a number average molecular weight in the range from about 500 to about 25,000 Daltons. 
     
     
         6 . The polymerization process of  claim 1 , wherein the ethyleneimine additive has a viscosity in the range from about 2000 to about 200000 cps as measured using a Brookfield viscometer at 20° C. 
     
     
         7 . The polymerization process of any one of  claims 1 - 6 , further comprising combining the ethyleneimine addititive with a mineral oil or an aromatic hydrocarbon to form at least a portion of the ethyleneimine additive used in the feeding. 
     
     
         8 . The polymerization process of  claim 7 , wherein the ethyleneimine additive is fed to the reactor as at least one of a suspension or a solution. 
     
     
         9 . The process according to any of the previous claims, wherein the polymerization reactor comprising a fluidized bed reactor, an entrainment zone, a catalyst feed for introducing a catalyst system capable of producing the polymer, at least one ethyleneimine additive feed for the feeding of the at least one ethyleneimine additive independently of the catalyst mixture, the process comprising: (a) contacting the at least one olefin with the catalyst system under polymerization conditions in the fluidized bed reactor; and (b) introducing the at least one ethyleneimine additive into the reactor system at anytime before, during, or after start of the polymerization reaction. 
     
     
         10 . The process of  claim 9 , further comprising: (c) monitoring a level of electrostatic activity in the entrainment zone; and (d) adjusting the amount of the at least one ethyleneimine additive introduced into the reactor system to maintain the levels of electrostatic activity in the entrainment zone at or near zero. 
     
     
         11 . The polymerization process of any preceding claim, wherein the polymerizing comprises feeding a metallocene catalyst, a Ziegler-Natta catalyst, a chromium based catalyst, or a mixed catalyst system to the polymerization reactor. 
     
     
         12 . The process of  claim 9  or  10 , wherein the catalyst system comprises at least one metallocene catalyst. 
     
     
         13 . The polymerization process of  claim 11 , wherein the mixed catalyst system is a bimetallic catalyst system. 
     
     
         14 . The process of any one of  claims 1 - 13 , wherein the polymerization reactor comprises a gas-phase reactor. 
     
     
         15 . The process of any one of  claims 1 - 14 , wherein the at least one olefin comprises at least one of ethylene and propylene. 
     
     
         16 . The process of  claim 15 , wherein the at least one olefin further comprises at least one C 4  to C 8  alpha olefin. 
     
     
         17 . A process for copolymerizing ethylene and one or more alpha olefins in a gas phase reactor utilizing a metallocene catalyst, activator and support, comprising:
 combining ethylene and one or more of 1-butene, 1-hexene, 4-methylpent-1-ene, or 1-octene in the presence of a metallocene catalyst, an activator and a support;   monitoring static in said reactor by at least one recycle line static probe, at least one upper bed static probe, at least one annular disk static probe, or at least one distributor plate static probe;   maintaining the static at a desired level by use of at least one ethyleneimine additive comprising a polyethyleneimine, an ethyleneimine copolymer, or a mixture thereof, the at least one ethyleneimine additive present in said reactor in the range from about 0.1 to about 50 ppm, based on the weight of polymer produced by said combining.   
     
     
         18 . A method for treating at least one interior surface of a fluidized bed polymerization reactor system, comprising:
 contacting at least one of a bed wall, a distributor plate, and a gas recycle line with a ethyleneimine additive comprising a polyethyleneimine, an ethyleneimine copolymer, or a mixture thereof to form a coating comprising the ethyleneimine additive thereupon;   performing a polymerization reaction in the fluidized bed polymerization reactor system comprising the coating.   
     
     
         19 . The method of  claim 18 , wherein the polymerization reaction is performed in the absence of added continuity additive. 
     
     
         20 . The method of  claim 18  or  19 , further comprising feeding at least one ethyleneimine additive comprising a polyethyleneimine, an ethyleneimine copolymer, or a mixture thereof to the polymerization reactor. 
     
     
         21 . A method for screening continuity additives for use in a polymerization reactor, comprising:
 combining at least one continuity additive with a polymerization catalyst system; and   measuring any exotherm resulting from the admixing.   
     
     
         22 . The method of  claim 21 , further comprising determining an effect of the continuity additive on polymerization catalyst productivity based upon the measured exotherm. 
     
     
         23 . A catalyst system comprising:
 at least one polymerization catalyst; and   a polyethyleneimine or an ethyleneimine copolymer.   
     
     
         24 . The catalyst system of  claim 23 , further comprising an activator. 
     
     
         25 . The catalyst system of  claim 24 , further comprising a support, wherein the at least one polymerization catalyst and the activator are supported by the support. 
     
     
         26 . The catalyst system of any one of  claims 23 - 25 , wherein the at least one polymerization catalyst comprises a metallocene catalyst, a Ziegler-Natta catalyst, a chromium based catalyst, or a mixed catalyst system. 
     
     
         27 . The catalyst system of  claim 26 , wherein the mixed catalyst system comprises a bimetallic catalyst.